The invention relates to a gas-insulated switchgear assembly, in particular a gas-insulated medium-voltage switchgear assembly.
In addition to a circuit breaker, which is usually installed in a fixed manner, electrical switchgear assemblies, in particular medium-voltage switchgear assemblies, also contain a disconnector, which is arranged, for example, between the circuit breaker and the bus bar current path. This disconnector can assume two or three positions: connected position, disconnected position and possibly grounding position. This disconnector is therefore in the form of a two-position or three-position disconnector.
In the connected position, a connection to the voltage-carrying busbar is produced and, in the grounding position, a connection to ground is produced, for example. In the disconnected position, the movable contact piece of the disconnector is located in a central position between the connected position and the grounding position.
Conventional three-position disconnectors are known as linear-travel switches or knife switches.
In general, disconnectors are used as an independent device in the same gas area as the circuit breaker or in a separate gas area, in particular in the case of double-busbar arrangements. The electrical part of these devices is always part of the gas area and is connected to the drive by means of a gas-tight bushing, which drive is usually located outside the gas area and is generally in the form of a mechanical drive in medium-voltage applications.
In the known double-busbar arrangements, firstly a three-position disconnector and secondly a two-position disconnector (no grounding position) are located in the two separate busbar areas.
Grounding of the outgoing section for the safety of operating personnel, for example during maintenance or installation work, takes place via the grounding position of the three-position disconnector and of the connected circuit breaker. Then, possibly further fitted grounding switches without any switching capacity can be introduced in order to allow for subsequent opening of the circuit breaker. Corresponding electrical and/or mechanical latching devices prevent both the grounding position of the three-position disconnector from being left unintentionally and disconnection of the circuit breaker (if no parallel grounding connection has been connected) and therefore ensure safe grounding of the outgoing section.
The switching positions are transmitted to position displays by means of elements which are mechanically coupled to the drive and are signaled by means of auxiliary switches or proximity sensors. In addition, further positions (such as the grounding position, for example) can be signaled in contactless fashion via reed contacts, which results in redundant position signaling with correspondingly increased reliability.
The visual checking of the switching position prescribed in some application areas by means of direct viewing contact of the switching device in the interior of a gas-insulated switchgear assembly is not possible depending on the construction, position and design, or the positions cannot be clearly identified.